Optimization of magnetic core structure for wireless charging coupler

The high coupling coefficient of wireless charging coupler can improve the transmission efficiency. To obtain higher coupling coefficient and lighter weight for double D (DD) coupler, the equivalent magnetic circuit and the expression of coupling coefficient are derived, which give some guidance for magnetic core optimization. Then different core structures are designed and compared by 3D Maxwell finite-element analysis. An optimized core structure is given and the experimental results show the validity. Then the theory method to evaluate charging zone is proposed, which gives a clear concept to confirm maximum vertical and horizontal offset.